Transmission systems generally have transmitter/receiver apparatus and a transmission facility interconnecting the transmitter/receiver apparatus and providing a path over which data may be exchanged between the transmitter/receiver apparatus. Increasing advances in technology and the need to exchange information in a short time interval require greater speed in the rate of transmitting data. The technology has went from analog systems to digital information systems capable of transmitting digital information in the form of "0's" and "1's" oftentimes referred to as bits. In an effort to increase the speed of transmission systems, the technology has advanced to the use of optical transmission systems using optical transmitter/receivers interconnected by optical transmission facilities such as optical fibers or laser systems that transmit optical pulse bit information between the optical transmitter/receivers.
Digital and optical transmission systems oftentimes have transmitter/receiver devices connected by transmission facilities all of which are subject to noise wherein noise may be any spurious or undesired disturbances that tend to disrupt the transmitted data by generating errors that obscure and mask the data information. During the design phase of the system special efforts are undertaken to design the apparatus to minimize noise. However, erratic disturbances normally beyond control of the designer, occur irregularly due to spontaneous fluctuations. These types of disturbances may be electromagnetic inferences, power supply problems, electrical storms, surges in voltages and the like.
Various techniques have been devised to measure errors and noise in communication and transmission systems. In some apparatus, data and a clock signal recovered from the data is applied to an error corrector and to a delay. A comparator compares the corrected data with the delayed data and outputs a pulse when the data are not coincident. The recovered clock signal is counted and when a predetermined number are counted, the apparatus latches the comparator generated pulses to obtain a received data bit error sum approximate number. In some apparatus, a sliding window is used wherein the number of error bits received during a predetermined of received bits is calculated to determine the bit error rate. In yet other systems, the bit error rate is monitored by integrating line bit-interleaved-parity indications over a length of time and sounding an alarm when the count exceeds a threshold.
Although apparatus has been disclosed for determining bit error rate the increasing need for faster transmission of information requires the development of apparatus and a method of improving the determination of noise and errors rates occurring in the transmitter/receivers and occurring during transmission of data over transmission facilities interconnecting the transmitter/receivers.